Being securely attached and willing to forgive your partner tends to promote greater relationship success. Though attachment and partner forgiveness are associated cross-sectionally, research has yet to investigate whether and how these positive relationship factors tend to codevelop over time. The current study examined cross-lagged effects and correlated changes in partner forgivingness and attachment across a 2-year period with two measurement occasions (n = 514 individuals). Additionally, dyadic analyses were conducted with a subsample of dyads in the study (n = 149 dyads). Individual level analyses evidenced negative cross-sectional and longitudinal associations between attachment-anxiety and forgivingness. Attachment-avoidance and forgivingness showed significant correlated changes over time. Dyadic level analyses showed that attachment-avoidance predicted partner forgivingness 2 years later but not vice versa. Findings suggest that longitudinal associations between attachment and forgivingness may take different forms at the individual and dyadic level.